Selector for machine-switching telephone systems.



F. ALDENDORPF.

SWITCHING TELEPHONE SYSTEMS, APPLICATION FILED 912028.1912.

v SELECTOR FOR MACHINE /f M45 1 97, y

//7 ve/wok E472 A/davdo Patented Mar. 16, 1915.

- cral oflices, a group FRITZ ALDENDORFF, 0F VIEUX DIEU, N

WESTERN ELECTRIC COMPANY, OF NEW YORK, N. Y.,

tumors.

EAR ANT'WEBP, BELGIUM, ASSIGNOB TO A CORPORATION OF SELECTOR FOE MACfiINE-SWITCHI'NG TELEPHONE SYSTEMS.

31,131,811, Specification of marked thereon, which forms a part of this specification.

The selectors forming the subject of this invention are adapted particularly for use in satellite or private branch exchange systems in which a telephone user may some- 20 times wish to establish-a connection through the connecting apparatus of a main or distant exchange and at other times desires a connection through the switching devices of a local or private exchange.

The object of the inventionis to enable a telephone user to automatically obtain connection at will with a free trunk leading to the connecting devices of either one of sevof trunks being provided for each oiiice and several such groups being connected to the fixed selector contacts of one and the same row. To attain this object the'test circuits of the selector are placed under the control of the subscriber connected to it and means are provided by which the subscriber, after the selector has selected an idle trunk in the first group, can restart the advance of the Y selector brushes to the next group without hunting, that is, by rendering the test circuit'in this group inoperative. When the brushes reach the second group-they will again commence to aiitomatically hunt for an idle trunk line in this group.

one. feature of "the invention consists'in the manner in which the controlling station is enabled to cause changes in the test circuit of. a trunk-huntingselector over a metallic circuit \vithout'using theearth or a third conductor as a return conductor. This accomplished by so arranging the testing device of the selector that it connects a switching magnet or relay between the limbs of the controlling line at the moment the Letter rec nt Patented Mar. 16, 1915.

Application filed December 28, 1912. Serial No. 739,054.

selector finds afree trunk. If the free trunk found is one ofa group desired by the party making the call the switching relay 1s caused to disconnect itself from the line at the moment when the loop leading to the controlling station is momentarily opened in sending the selecting impulses that direct themovements of further selectors used to build up the connection. If the trunk hunting selector is to be caused to travel on to another trunk group, the resistance of theloop is reduced at the controlling station and the ensuing increase of i current strength brings about a change of the test circuits of the selector, which causes the same to travel over all the contacts of a group and not to commence testing until it has reached another group. The switching device' that effects the circuit changes of the test circuits and that is connected between the limbs of the controlling line may consist of a relay having contacts some of v.1uchareactuated on the passage of a comparatively feeble current through the coils of the relay-and others thatrequire a stronger-current to move them.

Another feature of the invention consists in leading each of the groups of trunks of the various groups of contacts to a separate telephone system, each of the dilferent systems being excluded from communication with each other. By providing some telephone users with a trunk hunting selector giving access to several groups of trunks and others with selectors'giving access to one group of trunks only, a system can be arranged ,for different ranges of service, the telephone users of lesser importance being restricted to conversations in one telephone system, those of greater importance being able to obtain connections to a number of systems. In private branch exchange systems, for instance, the telephone users of gr ater importance would be given access to the city exchange system as well as to the private exchange system, while stations of lesser importance \voul d'bo given access to the private exchange system only.

in the drawing 1 represents a trunk hunt- Eng selector having movable contact arms 5, (E, 7 arranged to be rotated over sets of bank contacts '2, 3, l, and 2, 3, 4 by a turning magnet 8 with the aid of a ratchet and pawl mechanism not shown. Each of the sets eration of the selector.

of contacts 2,

3, 4c is connected to the wires representing a trunk 9 and eachset of contacts 2 3 st forms the terminals of a trunk 10. The trunks 9 and 10 lead to difiercnt telephone systems, 0. g. trunks 9 are represented as leading to group selectors and 10 are supposed to be leading to an operating position 12 in a system separate from that to which the group selector ll belongs. There may, of course, be anynumber of trunks 9 or 10 in a group. In the drawing, sull'icient bank contacts are shown for a group of three trunks leading to three selectors ll anrl for a group of two trunks 10 leading to tions 12.

13 represents the test relay of the selector 1; 1-1 is the relay that is connected between the limbs l8, 19 of the subscribers line and that gives the subscriber control over the test circuits. The relay ll has contacts 20 and 21 that act in response tively feeble current flowing through the relay windings and a ccntact 22 that requires zr'coinparatively strong current to close it.

an operators position or posilo, 1s a relay controlled byrelay Li and its function to change the circuits of the test relay 13 so as to stop the testing action of this relay, while the contact arms 5, 6, 7 are traveling over a particular group of trunks, e. g. 9, and to recommence testing on the next group being reached.

16 is aline relay under the control of the controlling station or subscriber 7 The subscribers station is represented merely y a resistance 7land a key 72' for short circuiting this resistance, it being assumed that, on the subscriber taking his receiver from the switch-hook (not shown), the usual apparatus required for talking and hearing is inserted in the loop, 2'. 6. between the Wires 18 and 19.

56 is an off normal iber impulse transin the d he significance of the other parts shown in the drawing and not described above will become clear from the description of the op When the subscriber closes the line circuit l8, 19 by removing his receiver from the switchhook, a current is caused to flow over the following path':- from the negative pole of battery, line relay l6, armature contact 23, line 18, .resistance 71, at subscribers station 70, line 19, contact 24 to the positive pole of the battery. The line relay l6 thereupon attracts its armature and closes the circuit of the turning magnetS, which includes an interrupter l7. The current through'the turning magnet flows from the positive pole of 'energization the battery, through interrupter 17, windings of magnet armature contact 25, arn1- ature contact 27, to the negative pole of battery. In response to each impulse caused by the interrupter 17, the ratchet and pawl device actuated by the turning magnet 8 moves the contact arms 5, 6, 7 of the selector around step by step, over the sets of contacts 2, 3, st in search of an idle trunk 9. The moment an idle trunk is found a current will flow from the negative pole of the battery group selector 11, through a resistance 28, bank contact 4, test arm 5, windings of test relay l3, armature contact 29, armature contact 30 to the positive pole of the battery. The completion of this circuit will cause the of the test relay l3 and the subsequent attraction of its armatures. Thus contact 23 will be opened and the circuit containing the line relay 16, previously completed, will be interrupted and the line relay 16 dec'nergizcd. The release of the line relay armatures will open the circuit containing the turning magnet 8 at contact 27, andalso the circuit containing the test relay 13 at contact 29; therefore the operation of the turning magnet 8 will cease and thus the contact arms 5, 6 and 7- will remain upon the idle trunk selected. The test relay 13 is net deenergized by the breaking of the circuit at contact 29 on line relay 16, as this part of the test relay circuit is substituted by a circuit which may be traced from the winding of relay 13, through contact 60 and contact 45 to the positive pole of the battery. By closing the contact 31, the test magnet 13 short circuits 0. part of its own winding and thus reduces the potential at the test bank contacts 4 so as to render the seized truhk engaged. If the calling subscriber. 70 desires a connection through the group selector 11, he will cause selecting impulses flow through the line by working his selector controller or impulse transmitting device immediately after raising his receiver. In the assumed system these impulses will be caused by interruptions in the loop l8-19 and will act upon controlling devices in the group selector 11, which as they form no part of this invention, are not shown.

It must now g5 explained that the test relay in attracting its armatures closed a circuit containing relay 1%, which may be traced as follows: from the positive pole of the battery through the three armature contacts 32, 33, 34;, relay 14, armature contact 20, armature contact 35, resistance 40 and the negative pole of the ba ttery. The armature contacts 32, 33 and 34: are so adjusted that contact 32 willi be completed before the the circuit containing relay 14, just traced, will be closed momentarily'only, and relay 14 will receive but a momentary actuation.

" ture contact 36, armature contact 37, line wire 19, resistance 71, line wire 18, wire-38,

contact 21, relay winding 14, resistance 39 and the negative pole of the battery. This circuit will be completed before the circuit caused. by the momentary actuation of relay 14 is broken at contact 20, since contact 21 will be closed before contact 20 is opened. The current that will flow through the relay '14 at the moment of its actuation by the closure of the contacts 32, 33, 34 will be suiiiciently weakened by resistance 40 to prevent closing of contact After the relay 14 has inserted its winding in the line circuit 18, 19 the resistance 71 also reduces 'the current strength suliiciently to prevent the closing oi contact 2-27 11? the line ircuit is now opened by the subscriber interrupting the loop in the act of sending in selecting impulses the relay 14 will be decnergized and the contacts 21 and 313 reopened, leaving a clear connection from the sul'iscribers line 18, 19 through the contacts 37 and 41 to the tact thron gh the ,being excited by positive pole of the battery through the congroup selector. If the subscriber instead of immediately sending in his selecting impulses first closes the contact 72 and shortcircuits the resistance 71 at his station, the current flowing through the relay 14 will be strengthened sufiiciently to cause it to pull up its heavier armature and to close the con- 22. This will excite the relay 15 following circuit: from the positive pole of the battery through contact 22, relay 15, oil normal switch 56, which is now closed, to the negative pole of the bat-- tery. The relay 15 will attract its ariuatures and close the co itacts42, 43 and 44 and open the contacts 45 and 30. Circuit changes are effected hereby, that cause the test relay 13 to release its armatures. It will he remembered that the test relay was a current flowing from the tact 45, winding of the relay 13, to the ncgativc pole of the battery at the group selector. By the contact 45 beii'ig opened and contact closed, the connection to the test relay 13 is changed from the positive to the negative pole oi'." the battery, and thus the same pole of battery isapplicd to both ends of the winding of the test relay 13. llence the test. relay is dei nergized'and the circuit for the turning magnet is again closed by a current llowingfroin the positive pole or the battery through the interrupter 17, turn ng magnet 8, contact 25, contact 27 to the negative pole of the battery. Contact 27 is, of course, closed again, for as soon as the test relay l3 releases its'armatures the line relay 1G will again be energized my current flowing through the subscribers loop.

is the test wires of all the trunks 9 are connected through a resistance 28 to the negative pole of the battery, the test relay will have the same pole of the battery applied to each end of its coil as long as the contact arms 5, 6, 7 traverse sets of bank contacts 2, 3, 4 connected to trunks leading to group selectors 11. The moment thebank contacts 2, 3 4 arereached the test relay 13 will commence testing again, because the test -wires 4 are connected through resistances 55 to the positive pole of the battery. The'moment a free trunk is found the test relay will be excited by a current flowing from the positive pole of the battery through a resistance 55, contact 53, armature 54, test contact 4 test contact arm 5, test relay 13, armature contact 29, armature contact 44 to 8 vthe negative pole of the battei y. The test relay in attracting its armatures opens the circuit of the turning magnet as before, and connects the subscribers loop 18, 19 through the contacts 41 and 37 to the talking wires 9 46 and to the contactarms 6, 7, which now extend the connection through the wires 47, 48 of the trunk 10 to a relay 49 at the operators position 12. The relay 49 will now be excited by a current flowing from 9 the positive pole of the battery through the wire 47, contact 2, contact arm '7, wire 46, armature contact 37, wire 19, subscribers station, wire18, contact 41, wire 45, contact arm 6, bank contact 3, wire 48 of trunk-10, l winding of relay 49 to the negative pole. The relay 49 attracts its armature and closes the contact 50 included in the circuit of a calling lamp 5]., thus attracting'the attention of the operator to the call. The operator answers the call in the manner usual in manual exchanges by inserting a plug in a jack 52. I

It must be pointed out that the armature 54 and its contact are so arranged that the 1 ittraction of this armaure will not open contact 53. When the subscriber at the finish of the connection replaces his receiver and thus opens his line loop, the relay 49 releases its armatures. The armature 54 in moving back to its normal position momentarily opens the contact '53 and de nergizes the test relay 13, which again closes the circuit of the turning magnet 8 at its contact 25, so that current impulses will flow 1 through the turning magnet from the positi ve pole of the battery through interrupter 17, turning magnet 8, contact contact 26, oil normal contact 56 to the negative pole of the battery. As the circuit of the test relay 1 13 is now open at the contact 29 of the line relay the test relay will not test for idle trunks and the turning magnet will continue steppin the contact arms 5, 6, 7 from one set of nr a!) ll'lk contacts to the nextuntil the contact arms are in their normal position,

i when the oil-normal switch 56 will be opened and the circuit of the turning magnet ,8 interr1 1pted. Theopening of the ottiiormal switch 56also opens the locking cir- ,cuitot the relayfil5fand thus causes all the parts of the selector-to return to their nor mal position. It ,vvill be clear that another group of trunks similar to 9 could be ar- 10 ranged, beyond the group 10, andthat the contact arms 5, 6, 7, after they have selected a, free trunk 10 could be caused to move on .tactarms have chosen a free trunk 10in the second group could be brought" about by a switch located at the point S in the Wire leading from the contact 42 of the relay l5 to the positive pole of the b ttery. If this switch S were placed at the ontrolling station 70 so that it could be opened at will at the station, the switch could be caused to recommence its travel by openingswitch S and causing the relay 15 to release its armatures.

I -Tbe positive pole of the battery would then again be connected. through the contact to-thecoil of the test relay l3 and as the :same pole of the battery is connected through the contacts 53 at the operating positions 12 to the other end. of the coil 13, the

ftest "relay would cease to test until it reached the next group of trunks similar to 9 that have the negative pole of the battery connected to them through resistances 28.

' 'jco ntacts has been described, it Will be clear- 40,

Although a selector with only one row of to all who are skilled in the art that selectors on the same principle could be built having several rows of contacts and ass lect ng magnet'lor causing the contact arms to hunt 1n any one of the several rows.

, rate branch exchange, the telephone users In a private establishment having a prigenerally Wish to call another part connefcted to the private exchange, and 0 not vsooft'en make calls through the public or city exchange. In an establishment of this kind there are usually two classes of service,

, most of the telephone users being confined 1 to telephonic communication Within theprivateestablishment, and others being pro- ;vided. with connecting facilities for both.

the private establishment and the public exchange. The trunk huntin selector de- ;scribed above is peculiarly adapted for'a. private system of this description; the subscribers that are to be, allowed unrestricted 3 connecting facilities would be provided with a trunk hunting selector as described above,

-from. which one group of trunks :lead to.

selectors of the private exchange, dtnd another group of trunks lead to th i public exchange. .he subscribers that are-to be allowed con ections through the private exchange only would he provided with trunk huntingselectors whichwill connect with but one group oftrunks,these trunks being Wired to theselectorsof theprivate branch exchange. f I

I claim i l 1. A trunk hunting selector for tele phone systems,comprising movable contacts, groups of fixed contacts arranged in a single row, each of the said groiuas of contacts being-connected to a different group of trunks, driving mcchanisu'i for driving said movable contacts over said row of contacts, means for causing said mechanism to stop the movable contacts at an idle trunk in'a group and :1V switching relay'under the controlof the subscriber which. will cause the advance of said movable contacts over said fixed contacts in the group Whether busy or idle. 1 I

2.'A trunk hunting selector for tele phone systems, comprising movable contacts, groups of fixed contacts each connected to a different group of trunk lines, said groups of contacts being arranged in a single row, mechanism for driving said movable contacis over said row of .hxed contacts, means for causing said mecl'ianism to stop the mov able contacts at an idle trunk in a group, means 101' causing the niovable'contacts to recommence traveling over any cBntact-s in the said group Whether busy or idle and means for-causing the said movable contacts to stop at a free line in the next group of contacts. v H

3. A trunk hunting selector for 'tcle loo phone systems comprising movable contacts Y groups of fixed contacts each connected tr. a different group of trunklines, said groups of contacts beingarranged in a single row,

mechanism for drivingsaid movable contacts over said row of fixed contacts. a test electro-magnet controlling saiddriving mechanism so as to cause it to stop acting Whenthe selector reacl PS a free trunk in a group, a line leading from the said trunk hunting selector to a controlling station, an electro magnet under the control of the said station for changing the oircuit of the said test electromagnet so as to render the driving mechanism uncontrollable by the said test electro-magnet until the sai movable contacts reach the next trunk grou 4 A trunk hunting selector for telephone systems comprising movable contactsggroups of fixed contacts al'range'd in a single row, each of the said groups of contacts being connected to a different group of trunks, a single metallic controlling circuit extenzlt .ing; from said trunk hunting selector to a, controlling station, driving inechanism'forv driving said movable contactsover saidrow of contacts, means for causing saidmechaans-inn advance of said movable contacts over said fiid 'contactsin the group whether busy or i le. v

5. A trunk hunting selector fortelephone systems comprising movable contacts, groups of fixed contacts arranged in a singled-ow, each of the said groups of contacts being connected to different groups of trunks, driving mechanism for driving said movable contacts over said row of contacts, a controlling circuit leading fromsaid trunk hunt ing selector to a controlling station, a test electro-inagnet for causing said mechanism F to stop the movable contacts at a tree trunk, a second electrosmagnet connected to said contrr lling circuit after the stopping of the movable contacts, means in the cont-rolling circuit for causing said second electro-magnet to restart the traveling (if the said movable contacts.

' 6. A trunk hunting selectoirfor telephone systems comprising movable contacts, groups of fixed contacts arranged in a, single iow, each of the said groups of contacts being connected to a different group of trunks, drivingmechanisni for driving said movzible contacts over said row of contacts, a controling selector-t0 a controlling station, a test electro-magnet for causing said mechanism to stop the movablecontacts'on a free trunk, a second electro-magnet connected to said controlling circuit on the stopping of the movable'contacts, an interrupter in the controlling circuit for causing the disconnection of the said second'electro-magnet from the said controlling circuit when this latter is extended to a free trunk.

7. In a telephone system, trunk hunting selectors comprising movable contacts, groups of fixed contacts arranged in a single row, each of the said groups of contacts being connected to a different group of trunks;

driving mechanism for driving said movable contacts over said row of contacts. means for causing said mechanism to stop the movable contacts on an idle trunk in a group, a switching relay under the control of the subscriber which will cause the advance of said movable contacts over said fixed contacts in a group whether busy or idle, and means to select the first idle trunk in the next group.

8.111 a branch exchange telephone systern, a trunk-hunting contact arm. a test circuit therefor, a group oi fixed contacts, trunk lines connected thereto. a second group of fixed contacts, trunk lines connected thereto, means for advancing said contact arm upon the initiation of a call to an idle trunk in the first group, means at the controlling station for automatically selecting a party overisaid trunk, and alternate means at the calling station to select one class of ling circuit leading from said trunk hunt at the substation for automatically advanc ing said selector to the next group by ren dering the test circuit inoperative and for hunting an idle trunk-in said second group. 9. In a branch exchange telephonesystem, groups of fixed contacts, trunk lines leading therefrom directed to different classes of service, trunlchunting contact arms cooperating with said contacts, means service, alternate means at the substation to'subsequently select another class of service, a bridged switching relay under the control of said second means, and means operated by said relay for switching said contact armh from one class of service to the next.

10. In a branch exchange telephone system, a group of fixed contacts, trunk lines connected thereto, a second group of fixed contacts, trunk lines connected hereto, trunk-huntin contact arms cooperating with said contacts, a test circuit therefor, means for advancing said contact arms, means for stopping said contact arms on an idle trunk,- a bridged switching relay which is partially operated by said means, means at the calling station for denergizing said relay, means'at the substation for increasing the (low of current in the line circuit and causing the complete operation of, said relay, and means controlled by said relay to automatically advance said'contact arms to the next group of contacts by rendering the test circuit inoperative and to hunt an idle trunk in said next group.

11. In a branch exchange telephone system, groups of fixed contacts. trunk lines directed to dill'ercntclasses or service connected to said contacts, a traveling trunkhunting terminal for testing the condition 105 of said contacts, and means at the calling station to control the terminal test circuit to render it inoperative for one class of service and operative for. another class of service. i I

12. In a branch exchange telephone system, a group of fixed contacts, trunk lines loading therefrom directed to a particular class of service, a second group of fixed contacts, trunk lines leading therefroin'and 115 directed to a ditlerent class of service, trunkhunting'contact armsya test circuit therefor, means for placing the test circuit under the control of the subscriber after the se- 'lection of an idle trunk in the first group,

and means to automatically advance said contact arms to the next group of contacts by render ng the test circuit inoperative and "for hunting an idle trunk in said next group.

' 13. In a branch exchange telephone to. subsequently render the test circuit in cause-them to test over busy and idle teroperative, means for advancing said selector minals of that class and connect With the to the next -group, and means for autofirst idle termlnal of another class.

matically hunting an idle trunk in said In Witness whereof, I hereuntosubscribe 5 group.

14. In a trunk selector, terminals. for different classes of trunks, traveling contacts for testing said terminals, means to' associate saidtraveling contacts with a set of Witnesses: idle terminals of one class, and means asso- G. DE LERSY, ciated With said contacts to subsequently I N. AnAMsI my name this 29th dayof November D." 1912.

FRITZ ALDENDOBFF. 

